The present invention relates to an intercooler mounted in a small planing, boat such as a motorboat or a recreational watercraft, which is provided on the upstream side of the engine air intake port and is employed to cool supercharging air.
While 2-cycle engines have been commonly used as drive engines in small planing boats in the prior art, we are seeing more 4-cycle engines which are quieter and more environmentally friendly mounted in small planing boats in recent years. In such a small planing boat, a supercharger must be installed in order to improve the combustion rate in the engine. When such a supercharger is employed, the temperature of the supercharging air rises to 120° C.˜130° C. and, thus, an intercooler must be provided to improve the engine output by cooling the supercharging air and thus increasing the air density.
It is mandated to provide a flame arrester in small planing boats in order to ensure that any backfire (the term “backfire” is hereafter used to refer to a flame propagating toward the air-intake side) does not blow out into the engine compartment, and Japanese Unexamined Patent Publication No. H 9-301271 and Japanese Unexamined Patent Publication No. H 10-258794 each disclose a structure having a flame arrester provided on the upstream side of a carburetor installed in the air intake path communicating with an air intake port of the engine.
However, as the engine is often mounted under a passenger seat in a small planing boat, even more rigorous measures must be taken to prevent any backfire from blowing out into the engine compartment. While such measures for preventing a backfire from blowing out into the engine compartment with a high degree of reliability may be achieved by providing a larger arrester device and thus improving the caloric capacity, the installation of a large arrester device in a small planing boat conflicts with its other essential requirements such as space saving and weight minimization.